This invention relates to liquid laundry detergent products which are non-aqueous in nature and which are in the form of stable dispersions of water-soluble particulate material and preferably also include other materials such as bleaching agents and/or conventional detergent composition adjuvants.
Liquid laundry detergent products offer a number of advantages over dry, powdered or particulate laundry detergent products. Liquid laundry detergent products are readily measurable, speedily dissolved in wash water, non-dusting, are capable of being easily applied in concentrated solutions or dispersions to soiled areas on garments to be laundered and usually occupy less storage space than granular products. Because liquid laundry detergents are usually considered to be more convenient to use than granular laundry detergents, they have found substantial favor with consumers.
However, while liquid laundry detergents have a number of advantages over granular laundry detergent products, there are also disadvantages entailed in using them. In particular, laundry detergent composition components which may be compatible with each other in granular products may tend to interact or react with each other in a liquid, and especially in an aqueous liquid, environment. Components such as peroxygen bleaches and bleach precursors can be especially difficult to incorporate into liquid laundry detergent products with an acceptable degree of compositional stability. Poor compositional stability may cause some active ingredients to react with each other prematurely in the product which can cause physical instabilities such as phase splitting, sedimentation and solidification. This premature reaction may also cause chemical instabilities which can lead to product discoloration or color change, oxygen gas liberation, oxidation of sensitive ingredients (especially enzymes) and eventually detersive performance loss.
One approach for enhancing the chemical compatibility and stability of liquid laundry detergent products has been to formulate non-aqueous (or anhydrous) liquid laundry detergent compositions. Generally, the chemical stability of the components of a non-aqueous liquid laundry detergent composition increases as the amount of water in the laundry detergent composition decreases. Moreover, by minimizing the amount of water in a liquid laundry detergent composition, one can maximize the surfactant activity of the composition. Non-aqueous liquid laundry detergent compositions have been disclosed in Hepworth et al., U.S. Pat. No. 4,615,820, Issued Oct. 17, 1986; Schultz et al., U.S. Pat. No. 4,929,380, Issued May 29, 1990; Schultz et al., U.S. Pat. No. 5,008,031, Issued Apr. 16, 1991; Elder et al., EP-A-030,096, Published Jun. 10, 1981; Hall et al., WO 92/09678, Published Jun. 11, 1992 and Sanderson et al., EP-A-565,017, Published Oct. 13, 1993.
However, certain common detergent ingredients such as builders and alkalinity sources (i.e. buffers) are not generally soluble in most non-aqueous solvents and because these ingredients are typically denser than the liquid matrix of a non-aqueous detergent composition, they have a tendency to separate out of liquid detergent products and form sediments on the bottom of the detergent container between their manufacture and usage by the consumer. This segregation can in turn have an adverse affect on product aesthetics, usage instructions, pourability, dispensability, stability and in particularly on the overall cleaning effectiveness.
Given the foregoing, there is a continuing need to formulate non-aqueous liquid laundry detergent compositions comprising ingredients (e.g. builders, alkalinity sources) which are insoluble in the non-aqueous detergent liquid without the undesirable separation and segregation phenomena discussed above. Accordingly, it is a benefit of the present invention to provide non-aqueous liquid laundry detergent compositions which have excellent cleaning and detersive performance without displaying deleterious separation and segregation phenomena.
It has now been discovered in the present invention that non-aqueous liquid laundry detergent compositions may contain ingredients which are insoluble in the liquid matrix of the detergent composition, without the undesirable separation and segregation of said insoluble ingredients by including, in addition to the insoluble ingredients, low-density particles which reduce the tendency of the insoluble ingredient particulates to separate out of the laundry detergent composition and sediment to the bottom of the detergent container. The low-density particles themselves are composed of a binding agent as well as one or more ingredients which are insoluble in the non-aqueous liquid matrix. These low-density particles have the further advantage that while they are insoluble in the non-aqueous liquid phase, they are completely soluble in water.
The non-aqueous liquid detergent compositions according to a first aspect of the present invention comprise from about 49% to about 99.95% by weight of the composition of a surfactant-containing non-aqueous liquid phase; and from about 0.05% to about 51% by weight of the composition of a suspended solid particulate phase. The suspended solid particulate phase, in particular, comprises low-density particles which are composed of a binding agent and materials selected from the group consisting of an alkalinity source, a chelant, a builder and mixtures thereof.
The present invention further encompasses a process for continuously preparing low-density particles comprising the steps of continuously mixing water, water-soluble binder and one or more particle ingredients to form an aqueous solution; and then subsequently drying the solution in a spray-dryer to from low-density particles having a substantially spherical shape and a particle size from about 1 xcexcm to 120 xcexcm.
The low-density particles of the present invention may also be used as one of the constituent detergent particles of a granular detergent.
All parts, percentages and ratios used herein are expressed as percent weight unless otherwise specified. All documents cited are, in relevant part, incorporated herein by reference.